Packed piston



FIG 2 ATTORNEY Dee. 28, 1954 s. c. COLLINS PACKED PISTON Filed June 2, 1952 United States Patent PACKED PISTON Samuel C. Collins,` Watertown, Mass., assiguorto Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Application June 2, 1952, Serial No. 291,083

Claims. (Cl. 309-23) This invention relates to a packed piston for a cylinderand-piston mechanism, especially to a carbon packed piston.

There are numerous industrial applications in which compressors are necessary, and in which it is highly de sirable that the compressors be operated without using the conventional hydrocarbon type of lubricants. ln order to get away from the use of such lubricants, many attempts have been made to provide non-metallic packing for the pistons of piston-and-cylinder mechanisms adapted, for example, to compress air for oxygen generators of the type disclosed in Win W. Pagets Patent No. 2,588,656, March l1, 1952. Such attempts have been largely unsuccessful, owing probably to the highly frangible quality of carbon piston rings.

It is an object of this invention to provide a carbon packed piston for a lcylinder-and-piston mechanism, in which the highly frangible carbon packing is designed to be subject to a minimum of distortion in use, and which is made in blocks designed to provide a minimum of stress concentrations. This and other objects are accomplished ina piston provided with packing or rings, the packing consisting of highly frangible non-metallic Vmaterial such as carbon, and being formed in blocks adapted to be biased by suitable resilient means outward into contact with the cylinder wall.

In the drawings:

Fig. l is a top plan view of a packed piston made according to the invention, this view being a partial section through the cylinder block.

Fig. 2 is a longitudinal section through a portion of a cylinder of a cylinder-and-piston mechanism made according to this invention, showing the piston largely in elevation but partially broken away and in section to show details.

Fig. 3 is a top plan view of the uppermost metallic disc shown in Fig. 2. V

Fig. 4 is a side elevation of the disc shown in Fig. 3.

Fig. 5 is a top plan view, partially broken away and in section, of the uppermost non-metallic packing member shown in Fig. 2.

Fig. 6 is an end elevation of the packing member shown in Fig. 5.

Fig. 7 is a top plan view of the second non-metallic packing member.

Fig. 8 is a top plan view of the lowermost piston member, this member being a metallic disc; Fig. 8 could also be a plan view of the non-metallic disc disposed immediately above the metallic disc, the non-metallic disc being slightly larger in diameter than the metallic disc in order to contact the cylinder wall; and

Fig. 9 is a view in elevation of the upper end of the piston rod.

A packed piston made according to this invention may be used in many of a large number of cylinder-and-piston mechanisms, and accordingly only ay small portion of such a mechanism is shown in the drawings. As there shown, a piston indicated generally at 2 is shown disposed in the cylinder 4 of a cylinder block indicated generally at 6.

The piston itself is composed of a plurality of discs and members suitably held together to form a piston generally known as of the trunk type. More specifically, a metallic disc 8 is shown at the very top of piston 2, disc 8 having in one side thereof a groove 10. A non-metallic member indicated generally at 12 is shown as comprising two block portions 12a and 12b relatively movable along a diameter 14. Each of the blocks 12a and 12b l 2,698,211 PatentedV Dec. 28, 1.954

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is recessed as shown at 16, each block being preferably provided withsuch a recess at opposite sides of the diameter 14. Resilient means are provided to expand the two portions 12a. and 12b outward into contact with the cylinder wall, these resilient means preferably taking the form of coil springs 18 disposed in the recesses 16.

The non-metallic member 12 is preferably made of a highly frangible substance such as carbon, and is of course adapted to have a sliding t in the groove 10 of the metallic disc 8. Disc 8 is provided with a central opening 2t) to receive the threaded portion 22 of a piston rod 24. Non-metallic member 12 is centrally bored or recessed as shown at 26. It will of course be understood by those skilled in the art that, when the non-metallic member 12 is new, the two substantially plane surfaces 28 and 30 are closely adacent each other, possibly even in actual contact, in which case the two recessed portions 26 cooperate to form a substantially circular opening to receive the reduced diameter portion 32 of the piston rod 24.

The threaded portion 22 of the piston rod 24 is preferably the smallest part of the piston rod, forming a shoulder at 34 with the portion 32, and the portion 32 is preferably smaller than the major part of the rod 24 forming therewith a shoulder 36.

A second non-metallic member is indicated generally at 38, and comprises two portions 38a and 38h. The two portions 38a. and 38h are relatively movable along a diameter 40, and are recessed at opposite sides of the diameter and provided with resilient means 42 in much the same manner as the non-metallic member 12. The non-metallic member 38 is of course also recessed as indicated at 44 in order to provide, when the member is new, a substantially central opening to receive the reduced diameter portion 32 of the piston rod.

It will `of course be understood by those skilled in the art that, in order to provide a maximum seal against blowby, the second non-metallic member 38 will preferably be oriented on the piston rod with its diameter 40 of .outward expansion disposed substantially at right angles to the diameter 14 of outward expansion of the member 12.

As can best be seen from Fig. 2, the second non-metallic member 38 has an upper surface adacent the first nonmetallic member 12 and also adjacent the grooved side of the metallic disc 8. A non-metallic disc 46 is disposed below the second non-metallic member 38 adjacent the remaining surface of member 38. The disc 46 is also preferably of a highly frangible substance such as carbon, being in this respect similar to the members 12 and 38. However, the disc 46 is a simple solid disc provided with a central opening 48 to receive the reduced diameter portion 32 of the piston rod.

The lowermost piece forming the piston consists simply of a metallic disc 50, disc 50 being a simple disc having a substantially central opening 52 to receive the reduced diameter portion 32 of the piston rod. As is best seen in Fig. 2, discs 8 and 50 are both made slightly smaller than the cylinder to permit unequal expansion without danger of rubbing contact between the discs 8 and 50 and the cylinder wall. The non-metallic disc 46, on the other hand, is provided with no such clearance, and preferably engages at its cylindrical peripheral surface the cylinder wall, at least when the disc 46 is new.

Means are provided to hold the several discs and members in assembled relation, these means comprising the aforesaid shoulder 36 and a nut 54 adapted to cooperate with the threaded portion 22 of the piston rod. The metallic disc 2 is preferably clamped between the shoulder 34 and the nut 54, and the proportions of the several discs and members are such that the non-metallic members 12 and 38 are not tightly clamped, but have a sliding tit with those pieces of the piston adjacent them in order to permit free outward expansion against the cylinder wall under-the influence of their resilient means 18 and 42 as wear takes place. It will of course be understood by those skilled in the art that the faces of members 12 and 38 are initially formed to have the contour of the cylinder wall with which they cooperate.

Mention was made above of the preferred orientation of diameter 40 substantially at right angles to diameter 14. In many cases a simple assembly of the various pieces with such an orientation will suice. In some cases,

however,"it 'willbe 'further desirable to provide `positive In operation, a packed piston made according to this inventioncan'bebused'without any of the conventional hydrocarbon lubricants. The highly frangible non- -metallic"packingmem'bers 12 and 38, being preferably of carbon, are expanded radially outward against the cylin der lwall-under the-'i-nuence of their resilient means'18 land 4Z. Asthe' members 12 and '38 wear, their resilient members ymovethem outward to keep them in contact with the cyli-ridenwall, eiiecting a substantially gastight seal.

many applications, the simple assembly of the mem- .bers'1`2 and "38 with their expansion axes or diameters 14 and 4l) substantially at right angles ywill suice to provide the desiredtgas 'tight sea-l. ln some applications, however, it will'be Aini-ther",desirable to provide the pin-and-slot Amechanism disclosed, and this mechanism will of course constrain' the non-'metallic member 3 8. in the desired orientation with respect V,tothe non-metallic member 12.

It will be evidentl to thoseI skilled'in the art that I have here provided an improved type of packed piston having ,numerous advantages, oneof which is its utility in an unlbricated cylinder-and-piston mechanism. Other advantages .will be apparent to thosefskilled in the art.

While therefis-in this application "specifically described onerfformjwhich' the invention may assume in practice, it "rlglbe imderstood thatthis form of the ,same is shown i urposes `of illustration, andA that the invention may bemoditied and em'I died in various other forms without departing from'its spirit or the scope of the appended l nani-eter, arid'resilientj means ,engaging xpan'glthe two portionsoutward into the ,t,op,0.-,. 1,15 contact"'w`ith"' member having iacesk,alapted` to' engagel'the cylinder wall andbeingadjacen Athe firstnamed 'nonmetallic member and'hviiagtwogndnins rielativlyrmovable along a Second ldiafneterand resilient 'means engaging the two porhelcyl'inder' wall; a 'sfeebnd non-metallic l 4 tions to expand the two portions outward along the second diameter; anon-metallic disc adjacent ythe tsecond-nonmetallic member; a second metallic disc adjacent the nonmetallic disc; and means to -hold the discs and non-metallic members together to form a piston.

2. A packed piston for a cylinder-and-piston mechanism comprising: a metallic ldisc having a groove in one side thereof; a non-,metallic member disposed in the groove and having faces adapted-to engage the cylinder wall, said member comprising two portions relatively movable in the groove ontwardalong a diameter, and resilient mean's engaging the two portions to expand the two portions outward into contact with the cylinder wall; a second nonmetallic `member having two surfaces one of which is adjacent the rst-na'med non-metallic member and adjacent the groovedside of the ,metallic .disc and having two portions relatively movable along a second diameter, and resilient means engaging the two portions to expand the two portions outward along the second diameter, the second non-metallic member'y :being so oriented that the-second diameter is disposed at substantially right angles t0 the ylrst-named diameter; .a non-metallic disc adjacent the second non-metallic member; ,a second metallic disc adjacent the non-metallic disc; and means to hold the discs and non-metallic members together to form a piston.

3. A packed .piston .as in claim 2 having `a pin-and-slot device .associated with the second non-metallic lmember and the first-named vmetallic disc.

4. A packed piston for a cylinder-and-piston mechanism comprising: a :metallic vdisc hav-ing a groove in one side thereof; a non-metallic highly rangible lmember havingtfaces :adapted to engage the cylinder wall and id isposed in the groove, said member comprising two poi:- tions relatively movable outward along a diameter, and resilient means .engaging the two yportions to expand the two, portions Ioutward finto contact with ,the cylinder wall;

a second non-metallic highly frangible lmember having faces adapted-:to engage .the cylinder'wall and being -adjcent the first such member and having two portions relatively movable along a second diameter, and resilient means to expand the two portions outward along the Ascond diameter, said'tsecond. member being so oriented that the second diameteris disposed -substantially at rightangles to the first-named diameter; a non-metallicV disc adjacent said secondA member; a second metallicdisc'djacent the non-metallic disc; and means't-o'hold the discs and members togetherto/forrn a piston. N' 5. A packedlpiston as in claim 4 yhaving means'totconstrain'saidsecond'member in the stated orientation.

References Cited in the tile of this patent UNITED STATES PATENTS.

Number Name Date 451,850 Blessing Nlay "5,"V i891 '1,898,845 Meyer` L Feb. '21., 1933 2,020,426 Meyer Nov. V1 2", 193.5 2,092,087 Saharoft' v Slept. 7, 1237 

